Table of contents
1. Concept
HTTP (hypertext transport protocol) protocol; called Hypertext Transfer Protocol in Chinese,
is an application layer communication protocol based on TCP/IP.
This protocol specifies in detail the rules for mutual communication between the browser and the World Wide Web server.
The agreement mainly stipulates two aspects:
- Client: used to send data to the server, which can be called a request message
- Server: Returns data to the client, which can be called a response message
2. Composition of request message
- request line
- Request header
- blank line
- Request body
3. Composition of response message
-
response line
HTTP/1.1 200 ok
and some status codes, reference: https://developer.mozilla.org/zh-CN/docs/Web/HTTP/Status -
response header
Cache-Control:缓存控制 private 私有的，只允许客户端缓存数据 Connection 链接设置 Content-Type:text/html;charset=utf-8 设置响应体的数据类型以及字符集,响应体为html，字符集 utf-8 Content-Length:响应体的长度，单位为字节 -
blank line
-
response body
-
The types of response body content are very flexible. Common types include HTML, CSS, JS, images, and JSON.
4. Create http service
Create HTTP service using nodejs
4.1 Operation steps
//1. 导入 http 模块
const http = require('http');
//2. 创建服务对象 create 创建 server 服务
// request 意为请求. 是对请求报文的封装对象, 通过 request 对象可以获得请求报文的数据
// response 意为响应. 是对响应报文的封装对象, 通过 response 对象可以设置响应报文
const server = http.createServer((request, response) => {
//解决中文乱码
response.setHeader("Content-Type","text/html;charset=utf-8")
response.end('Hello HTTP server');
});
//3. 监听端口, 启动服务
server.listen(9000, () => {
console.log('服务已经启动, 端口 9000 监听中...');
});
Execution timing of the callback function in http.createServer: When an HTTP request is received, it will be executed
4.2 Precautions
-
Command line ctrl + c to stop the service
-
After the service is started, the updated code must be restarted to take effect.
-
Solution to Chinese garbled response content
response.setHeader('content-type','text/html;charset=utf-8'); -
Port number is occupied
Error: listen EADDRINUSE: address already in use :::90001) Close the service currently running on the listening port (used more)
2) Modify other port numbers -
The default port of HTTP protocol is 80. The default port of the HTTPS protocol is 443, and the commonly used ports for HTTP service development are 3000, 8080
, 8090, and 9000.
5. Obtain HTTP request message
To obtain the requested data, you need to pass the request object
| meaning | grammar |
|---|---|
| Request method | request.method |
| Request version | request.httpVersion |
| Request path | request.url |
| URL path | require(‘url’).parse(request.url).pathname |
| URL query string | require(‘url’).parse(request.url, true).query |
| Request header | request.headers |
| Request body | request.on(‘data’, function(chunk){}) |
| Request method | request.method request.on(‘end’, function(){}); |
Precautions:
- request.url can only obtain the path and query string, but cannot obtain the domain name and protocol content in the URL.
- request.headers converts the request information into an object and converts the attribute names into "lowercase"
- About the path: If you only fill in the IP address or domain name information when accessing the website, the requested path is "/"
- About favicon.ico: This request is a request automatically sent by the browser
5.1 Get the request message
//1. 导入http模块
const http = require('http');
//2.创建服务对象 create 创建 server 服务
const server = http.createServer((request,response)=>{
//1.获取请求方法
console.log(request.method);
//2.获取http版本
console.log(request.httpVersion);
//3.获取请求路径
console.log(request.url);
//4.获取请求头
console.log(request.headers);
// 响应内容中文乱码的解决办法
response.setHeader('content-type','text/html;charset=utf-8');
response.end("你好啊");
})
//3.监听端口，启动服务
server.listen(8080,()=>{
console.log("服务已经启动");
})
5.2 Extract path and query string
Method 1: Introduce the url module
//1. 导入http模块
const http = require('http');
//导入url模块
const url = require('url');
//2.创建服务对象 create 创建 server 服务
const server = http.createServer((request,response)=>{
//解析request.url
// console.log(request.url);
let res = url.parse(request.url,true);
//路径
console.log(res.pathname);
//查询字符串
console.log(res.query.wd);
response.end('url')
})
//3.监听端口，启动服务
server.listen(9000,()=>{
console.log("服务已经启动");
})
Method 2: Instantiate the URL object
//1. 导入http模块
const http = require('http');
//2.创建服务对象 create 创建 server 服务
const server = http.createServer((request,response)=>{
//实例化url对象
let url = new URL(request.url,'http://127.0.0.1:9000');
//路径
console.log(url.pathname);
//查询字符串
console.log(url.searchParams.get('wd'));
response.end('url new ')
})
//3.监听端口，启动服务
server.listen(9000,()=>{
console.log("服务已经启动");
})
6. Set HTTP response message
| effect | grammar |
|---|---|
| Set response status code | response.statusCode |
| Set response status description | response.statusMessage (very rarely used) |
| Set response header information | response.setHeader('header name', 'header value') |
| Set response body | response.write(‘xx’) or response.end(‘xxx’) |
write 和 end 的两种使用情况：
//1. write 和 end 的结合使用 响应体相对分散
response.write('xx');
response.write('xx');
response.write('xx');
response.end(); //每一个请求，在处理的时候必须要执行 end 方法的
//2. 单独使用 end 方法 响应体相对集中
response.end('xxx');
Sample code:
//1.导入http模块
const http = require('http');
//2.创建对象
const server = http.createServer((request,response)=>{
//设置响应状态码
response.statusCode = 203;
//响应状态描述
response.statusMessage = "hello world"
//设置响应头
response.setHeader('content-type','text/html;charset=utf-8');
response.setHeader('test',['a','b','c']);
//设置响应体 ,write可以写多次，end只能出现一次
response.write("write写入");
response.write("write写入");
response.write("write写入");
response.end('end写入')
})
//3.监听端口，开启服务
server.listen(9000,()=>{
console.log("服务已启动")
})
7. MIME setting resource type
//1.导入http模块
const http = require('http');
//引入fs
const fs = require('fs');
//引入path模块
const path = require('path');
//mime类型数组
let mime = {
html: 'text/html',
css: 'text/css',
js: 'text/javascript',
png: 'image/png',
jpg: 'image/jpeg',
gif: 'image/gif',
mp4: 'video/mp4',
mp3: 'audio/mpeg',
json: 'application/json'
}
//2.创建对象
const server = http.createServer((request,response)=>{
let {
pathname} = new URL(request.url,'http://127.0.0.1:9000')
//拼接路径
let filepath = __dirname + pathname;
//异步fs读取
fs.readFile(filepath,(err,data)=>{
if(err){
response.end('响应失败');
return;
}
//获取文件后缀
let ext = path.extname(filepath).slice(1);
//获取mime类型
let type = mime[ext];
type?response.setHeader("content-type",type+';charset=utf-8'):
response.setHeader("content-type","application/octet-stream");
response.end(data);
})
})
//3.监听端口，开启服务
server.listen(9000,()=>{
console.log("服务已启动")
})